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-rw-r--r--src/lib/seq-set-builder.c113
1 files changed, 113 insertions, 0 deletions
diff --git a/src/lib/seq-set-builder.c b/src/lib/seq-set-builder.c
new file mode 100644
index 0000000..b5649b7
--- /dev/null
+++ b/src/lib/seq-set-builder.c
@@ -0,0 +1,113 @@
+/* Copyright (c) 2021 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "str.h"
+#include "seq-set-builder.h"
+
+struct seqset_builder {
+ string_t *str;
+ uint32_t last_seq;
+ size_t last_seq_pos;
+ size_t prefix_length;
+};
+
+struct seqset_builder *seqset_builder_init(string_t *str)
+{
+ struct seqset_builder *builder;
+ builder = i_new(struct seqset_builder, 1);
+ builder->str = str;
+ builder->last_seq = 0;
+ builder->prefix_length = str_len(str);
+ builder->last_seq_pos = 0;
+ return builder;
+}
+
+static void
+seqset_builder_append_one(struct seqset_builder *builder, uint32_t seq)
+{
+ builder->last_seq_pos = str_len(builder->str)+1;
+ str_printfa(builder->str, "%u,", seq);
+}
+
+static void
+seqset_builder_create_or_merge_range(struct seqset_builder *builder,
+ uint32_t seq)
+{
+ char delimiter = '\0';
+
+ i_assert(builder->last_seq_pos > builder->prefix_length);
+
+ str_truncate(builder->str, builder->last_seq_pos-1);
+
+ /* Get the delimiter from the builder string */
+ if (str_len(builder->str) > 0 &&
+ str_len(builder->str) - 1 > builder->prefix_length)
+ delimiter = str_data(builder->str)[str_len(builder->str) - 1];
+
+ if (delimiter == ':') {
+ seqset_builder_append_one(builder, seq);
+ } else if (delimiter == ',' || delimiter == '\0') {
+ str_printfa(builder->str, "%u:", builder->last_seq);
+ builder->last_seq_pos = str_len(builder->str) + 1;
+ str_printfa(builder->str, "%u,", seq);
+ } else
+ i_unreached();
+ return;
+}
+
+void seqset_builder_add(struct seqset_builder *builder, uint32_t seq)
+{
+ if (builder->last_seq == 0) {
+ /* No seq was yet appened so just append this one */
+ seqset_builder_append_one(builder, seq);
+ } else if (builder->last_seq + 1 == seq) {
+ /* This seq is following directly on the previous one
+ try to create a range of seqs */
+ seqset_builder_create_or_merge_range(builder, seq);
+ } else {
+ /* Append this seq without creating a range */
+ seqset_builder_append_one(builder, seq);
+ }
+ builder->last_seq = seq;
+}
+
+bool seqset_builder_try_add(struct seqset_builder *builder, size_t max_len,
+ uint32_t seq)
+{
+ /* Length of this sequence to be appended */
+ unsigned int seq_len = 0;
+ /* Buffer to use when calculating seq length as string */
+ char seq_str[MAX_INT_STRLEN];
+ /* Current length of the seq string */
+ unsigned int builder_str_len = str_len(builder->str);
+
+ if (builder->last_seq + 1 == seq && builder_str_len + 1 <= max_len) {
+ /* Following sequence: This seq can't grow the overall length
+ by more than one. */
+ seqset_builder_add(builder, seq);
+ return TRUE;
+ }
+
+ if (builder_str_len + MAX_INT_STRLEN + 1 <= max_len) {
+ /* Appending the maximum length of a sequence number and ','
+ still fits into max_len. There is no need to check the
+ actual length. */
+ seqset_builder_add(builder, seq);
+ return TRUE;
+ }
+
+ seq_len = strlen(dec2str_buf(seq_str, seq)) + 1;
+ if (seq_len + builder_str_len > max_len)
+ return FALSE;
+
+ seqset_builder_add(builder, seq);
+ return TRUE;
+}
+
+void seqset_builder_deinit(struct seqset_builder **builder)
+{
+ /* If anything was appened to the string remove the trailing ',' */
+ if ((*builder)->last_seq != 0)
+ str_truncate((*builder)->str, str_len((*builder)->str) - 1);
+ i_free(*builder);
+}